A strong cold front and upper level trough of low pressure pushed southeast into the central U.S. during the evening of the 12th into the day of the 13th.  The situation was somewhat complicated by several rounds of convection.  During the previous night, a wave of low pressure lifted northeast along the front  through southeast South Dakota into southwest Minnesota.  An area of severe thunderstorms occurred with this wave.  An outflow boundary pushed southeast from the cluster of storms.  It was evident by 1000 UTC to 1100 UTC on the Slater Profiler as the 850 mb winds shifted to the northwest at 30 to 40 kts.  The outflow boundary arched northeast to southwest through the state.  Thunderstorms fired along this boundary before sunrise and dropped penny size hail in Ringgold County.  In the meantime, the coldfront was slowing down as another wave formed along it in Kansas.  A 50 kt jet was evident at 850 mb pushing northeast out of Kansas into Iowa.  The environment during the day on the 13th showed a lifted index around -6 C. with shear values around 45 kts.  There was moderate instability with 1500 to 2500 J/kg present.  The freezing level was in the 13,500 to 14,000 foot range across the southeast half of the CWA.  The shear that was present was mainly in the form of speed shear as the profile was quite unidirectional.  Numerous thunderstorms formed throughout the day on the 13th and continued into the evening hours.  The storms remained below severe limits for the most part, but did occasionally break through with high winds and some hail.  Spotty reports of three quarter to one inch diameter hail were received.  One inch diameter hail covered Iowa Highway 5 near Centerville.  A cluster of storms produced high winds as it raced northeast across the northeast part of the CWA.  Winds of 60 to over 75 MPH were reported with these cells.  A wind speed of 77 MPH was measured in Butler County.  The high winds blew down a barn in Bremer County near Plainfield.   There was extensive damage in the Plainfield area to both trees and buildings as a second wind gust swept through the area.   The schoolnet site in Plainfield measured a wind gust of 103 MPH with the storm.

Thunderstorm Wind in BUTLER, IOWA
From 13-SEP-05 13:43:00 to 13-SEP-05 13:43:00 (CST)
Location: SHELL ROCK
Magnitude: 61 EG
Property damage: 3K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BREMER, IOWA
From 13-SEP-05 14:00:00 to 13-SEP-05 14:00:00 (CST)
Location: PLAINFIELD
Magnitude: 61 EG
Property damage: 35K
Crop damage: 5K
Reported by: BROADCAST MEDIA

Hail in RINGGOLD, IOWA
From 13-SEP-05 05:14:00 to 13-SEP-05 05:14:00 (CST)
Location: DIAGONAL
Magnitude: 0.75 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in RINGGOLD, IOWA
From 13-SEP-05 10:38:00 to 13-SEP-05 10:38:00 (CST)
Location: BEACONSFIELD
Magnitude: 0.88 
Property damage: 1K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in CASS, IOWA
From 13-SEP-05 11:50:00 to 13-SEP-05 11:50:00 (CST)
Location: CUMBERLAND
Magnitude: 0.75 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BREMER, IOWA
From 13-SEP-05 13:35:00 to 13-SEP-05 13:35:00 (CST)
Location: WAVERLY
Magnitude: 61 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BUTLER, IOWA
From 13-SEP-05 13:36:00 to 13-SEP-05 13:36:00 (CST)
Location: CLARKSVILLE
Magnitude: 67 MG
Property damage: 5K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BREMER, IOWA
From 13-SEP-05 13:38:00 to 13-SEP-05 13:38:00 (CST)
Location: PLAINFIELD
Magnitude: 50 MG
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in BREMER, IOWA
From 13-SEP-05 13:39:00 to 13-SEP-05 13:39:00 (CST)
Location: WAVERLY
Magnitude: 59 MG
Property damage: 5K
Reported by: GENERAL PUBLIC

Thunderstorm Wind in BREMER, IOWA
From 13-SEP-05 13:40:00 to 13-SEP-05 13:40:00 (CST)
Location: PLAINFIELD
Magnitude: 90 MG
Property damage: 150K
Crop damage: 25K
Reported by: AWOS,ASOS,MESONET,ETC

Hail in APPANOOSE, IOWA
From 13-SEP-05 18:52:00 to 13-SEP-05 18:52:00 (CST)
Location: CENTERVILLE
Magnitude: 1.00 
Property damage: 5K
Crop damage: 10K
Reported by: BROADCAST MEDIA

Hail in WAPELLO, IOWA
From 13-SEP-05 19:38:00 to 13-SEP-05 19:38:00 (CST)
Location: CHILLICOTHE
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER